RE: Deliberately create slow SSH response?

Kevin,

Check out fail2ban at http://sourceforge.net/projects/fail2ban -- it
will scan your logs for invalid access attempts and add iptables
firewall rules to block the offending IP addresses after a configurable
number of attempts.

This might seem like a strange question to ask, but is there a way to
deliberately create a slow response to an SSH request? I'm annoyed at
the large number of distributed SSH brute-force attacks on a server I
administer, trying to guess the password for 'root' and other accounts.
I think that my server is pretty secure; doesn't allow root to log in
through SSH, only a restricted number of accounts are allowed SSH
access, with I think pretty good passwords. But still, the attempts
annoy me.

I wouldn't mind if SSH took say 30 seconds to ask me for my password.
This would slow the attempts. Is there any way to configure OpenSSH to
do this? I searched the archives of this group with 'slow' and 'delay'
but didn't come up with anything on this topic. Please point it out to
me if I overlooked anything. In addition, I can limit the number of SSH
connections to 3-5 and still operate okay.

Ultimately, I need this solution for hosts running OpenSSH_3.9p1 under
RHEL ES 4 and OpenSSH_4.3p2 under Debian 'etch' 4.0 and Fedora Core 6.

RE: Deliberately create slow SSH response?

Thought of moving to a different port? Granted, if they
port-sweep your IP, they might find where you've moved off to, but it
will cut WAY down on the hits (especially if you pick something from
the well-known list that is normally innocuous, like, oh, port 1, 70,
179, etc.), and it's a one-line change to your sshd_config (well, that
and training yourself to ssh onto the other port... '-p' or '-P'
options depending on what you're trying to do).

-Michael

|> From: listbounce@securityfocus.com [mailto:listbounce@securityfocus.com]
|> On Behalf Of Zembower, Kevin
|> Sent: Wednesday, July 09, 2008 12:56 PM
|> To: secureshell@securityfocus.com
|> Subject: Deliberately create slow SSH response?
|>
|> This might seem like a strange question to ask, but is there a way to
|> deliberately create a slow response to an SSH request? I'm annoyed at
|> the large number of distributed SSH brute-force attacks on a server I
|> administer, trying to guess the password for 'root' and other accounts.
|> I think that my server is pretty secure; doesn't allow root to log in
|> through SSH, only a restricted number of accounts are allowed SSH
|> access, with I think pretty good passwords. But still, the attempts
|> annoy me.
|>
|> I wouldn't mind if SSH took say 30 seconds to ask me for my password.
|> This would slow the attempts. Is there any way to configure OpenSSH to
|> do this? I searched the archives of this group with 'slow' and 'delay'
|> but didn't come up with anything on this topic. Please point it out to
|> me if I overlooked anything. In addition, I can limit the number of SSH
|> connections to 3-5 and still operate okay.
|>
|> Ultimately, I need this solution for hosts running OpenSSH_3.9p1 under
|> RHEL ES 4 and OpenSSH_4.3p2 under Debian 'etch' 4.0 and Fedora Core 6.
|>
|> Thanks in advance for your advice and suggestions.
|>
|> -Kevin
|>
|> Kevin Zembower
|> Internet Services Group manager
|> Center for Communication Programs
|> Bloomberg School of Public Health
|> Johns Hopkins University
|> 111 Market Place, Suite 310
|> Baltimore, Maryland 21202
|> 410-659-6139